/****************************************************************************
 Copyright (c) 2021 Xiamen Yaji Software Co., Ltd.

 http://www.cocos.com

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated engine source code (the "Software"), a limited,
 worldwide, royalty-free, non-assignable, revocable and non-exclusive license
 to use Cocos Creator solely to develop games on your target platforms. You shall
 not use Cocos Creator software for developing other software or tools that's
 used for developing games. You are not granted to publish, distribute,
 sublicense, and/or sell copies of Cocos Creator.

 The software or tools in this License Agreement are licensed, not sold.
 Xiamen Yaji Software Co., Ltd. reserves all rights not expressly granted to you.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
****************************************************************************/

#include "primitive/Sphere.h"

namespace cc {
IGeometry sphere(float radius, const cc::optional<ISphereOptions> &opts) {
    const uint32_t segments = opts.has_value() ? opts->segments : 32;

    // lat === latitude
    // lon === longitude

    ccstd::vector<float>    positions;
    ccstd::vector<float>    normals;
    ccstd::vector<float>    uvs;
    ccstd::vector<uint32_t> indices;
    const Vec3              minPos(-radius, -radius, -radius);
    const Vec3              maxPos(radius, radius, radius);
    const float             boundingRadius = radius;

    for (uint32_t lat = 0; lat <= segments; lat++) {
        const float theta    = static_cast<float>(lat) * math::PI / static_cast<float>(segments);
        const float sinTheta = sin(theta);
        const float cosTheta = -cos(theta);

        for (uint32_t lon = 0; lon <= segments; ++lon) {
            const float phi    = static_cast<float>(lon) * 2.F * math::PI / static_cast<float>(segments) - math::PI / 2.F;
            const float sinPhi = sin(phi);
            const float cosPhi = cos(phi);

            const float x = sinPhi * sinTheta;
            const float y = cosTheta;
            const float z = cosPhi * sinTheta;
            const float u = static_cast<float>(lon) / static_cast<float>(segments);
            const float v = static_cast<float>(lat) / static_cast<float>(segments);

            positions.emplace_back(x * radius);
            positions.emplace_back(y * radius);
            positions.emplace_back(z * radius);

            normals.emplace_back(x);
            normals.emplace_back(y);
            normals.emplace_back(z);

            uvs.emplace_back(u);
            uvs.emplace_back(v);

            if ((lat < segments) && (lon < segments)) {
                const uint32_t seg1 = segments + 1;
                const uint32_t a    = seg1 * lat + lon;
                const uint32_t b    = seg1 * (lat + 1) + lon;
                const uint32_t c    = seg1 * (lat + 1) + lon + 1;
                const uint32_t d    = seg1 * lat + lon + 1;

                indices.emplace_back(a);
                indices.emplace_back(d);
                indices.emplace_back(b);

                indices.emplace_back(d);
                indices.emplace_back(c);
                indices.emplace_back(b);
            }
        }
    }

    IGeometry info;
    info.positions      = positions;
    info.normals        = normals;
    info.uvs            = uvs;
    info.boundingRadius = boundingRadius;
    info.minPos         = minPos;
    info.maxPos         = maxPos;
    info.indices        = indices;
    return info;
}

} // namespace cc
